Vitamin K2: 9 Uses and Benefits

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Vitamin K2 is an essential vitamin that many people never hear of until they have their first child and the nurse administers a Vitamin K injection.

Sadly, this essential nutrient is often overlooked, and it is important at all life stages, not just for newborn babies or pregnant moms. Other vitamins and minerals like Vitamin D, Magnesium and Calcium get the attention they deserve, but K2 is often ignored with dire consequences.

What is Vitamin K2?

Vitamin K is a fat soluble vitamin that is important for blood clotting and that contributes to a healthy heart, bones and immune system.

There are several different forms, mainly K1 and K2, though they act differently in the body:

  • Vitamin K1– (or phylloquinone) is natural form found in greens and nettle that is used by the liver for proper blood clotting.
  • Vitamin K2– (or menaquinone) is a more absorbable form of Vitamin K found in certain fermented foods and supplements is used by soft tissues and is helpful for bones, heart tissue and more
  • Vitamin K3– (or menadione) is a synthetic form of Vitamin K. This is typically the one injected into infants at birth and some studies have shown potential toxicity from this form

Which Form of Vitamin K2 is Best?

Vitamin K1 is found in leafy greens, though only a small amount is actually absorbed and used by the body. In fact, experts suggest that only 10% of Vitamin K1 from greens is used by the body.

Vitamin K2 is found in fermented raw grass fed dairy and certain other fermented foods (like natto). This is because K2 is a product of the fermentation and is created by certain bacteria. In general, these foods contain a proportionately lower amount of K2 (compared to the K1 in greens), though much more is absorbed. (1)

Interestingly, studies have shown great health and cardiovascular benefits from K2, but hardly any effect from K1. K1 is necessary for proper blood clotting and is used by the liver, while K2 benefits the bones and controls proper utilization of calcium. In fact, it is helpful to think of them as two separate nutrients with different purposes.

There is also a misconception that the body can convert K1 to K2. The research actually showed that while some other animals can effectively convert K1-K2, humans need food or supplemental sources of K2 for good health. (2)

Chris Kresser explains why the K1->K2 conversion is not effective in humans:

It was once erroneously believed that intestinal bacteria are a major contributor to vitamin K status. However, the majority of evidence contradicts this view. Most of the vitamin K2 produced in the intestine are embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. (Unden & Bongaerts, 1997, pp. 217-234)

Are We Deficient in Vitamin K?

Estimates are that over half of the adult population is deficient in Vitamin K.

While the effects of Vitamin K deficiency can show up in more serious problems like cardiovascular disease, bone loss and tooth decay, it can also manifest in smaller symptoms like easy bruising, heavy periods, or nosebleeds.

Those with digestive problems or with a history of antibiotic use are the most at risk for these problems.

In general, it would be a good idea to get adequate K1 and K2 from diet and supplements, though K2 is the most studied and effective for the benefits listed below.

For the rest of this post, I’ll be using the terms “Vitamin K” and “K2” to refer to the K2 form of Vitamin K.

Uses for Vitamin K2

So why is Vitamin K so important for optimal health anyway?

1. For Healthy Bones

Research has shown that Vitamin K2 is one of the most important nutrients for long-term bone health and that it is even more important than calcium.

K2 is needed to help calcium and other minerals bind into the bone matrix to strengthen bones (and not to stay in soft tissue where it can cause calcification in the wrong places).

In fact, studies have shown that Vitamin K is effective at not just stopping bone loss in people with osteoporosis but potentially reversing it as well.(3) This same research found up to an 80% reduction in fractures in osteoporosis patients with K2 supplements.

2. For Heart Health

I wrote before about how calcification of the arteries can occur when a person consumes too much calcium without the needed cofactors in the right ratios: Magnesium, Vitamin K2 and Vitamin D3.

The book Vitamin K and The Calcium Paradox details how Vitamin K is needed to usher calcium into bones and other necessary places in the body and keep it out of soft tissue, arteries and the heart. Magnesium is also important for this process and without the needed K2, D3 and magnesium, calcification is more likely.

It is important to note that the research only shows a cardiovascular benefit from K2 and not K1. In fact, the Rotterdam study found that those with the highest dietary or supplemental intake of K2 had the lowest risk of calcification of the arteries, and the lowest risk of getting or dying from cardiovascular disease.

With the drastic rise of heart disease in recent decades, Vitamin K is becoming an ever-important topic.

3. For Oral Health

Oral health is vital for overall health and Vitamin K is important for oral health. In fact, Vitamin K was one of the vitamins that Dr. Weston A. Price found was vital for tooth remineralization and prevention of cavities.

I used it as part of my tooth remineralization process that helped me reverse several small cavities. (I recently confirmed that remineralization is possible in an interview with a dentist who specializes in this process- listen here)

4. To Reduce Varicose Veins

This will be getting its own post soon, but the same action that makes Vitamin K beneficial for bone health may also make it helpful for those with varicose veins. (4)

Human research is still in the early stages, but we know that Vitamin K is needed for the production of MGP (matrix GLA protein), which helps avoid calcification in the arteries. This same protein helps stop calcification in the veins as well since the calcium meant for the bones is ushered into the bones and does not accumulate in veins and arteries.

The preliminary study published in the Journal of Vascular Research found that Vitamin K2 was necessary in reversing the chemical change and avoiding or getting rid of varicose veins.

More research is needed, but since Vitamin K has so many other benefits, it might be worth trying for those who struggle with varicose veins.

5. To Reduce Cancer Risks

There are several well-documented studies that show a correlation between higher Vitamin K consumption and lower risk of certain cancers:

  • A European cohort study showed that K2 may reduce the risk of prostate cancer by 35%  (5)
  • A follow up study showed a 63% reduced risk of prostate cancer in those with the highest Vitamin K intake vs. the lowest (6)
  • A 2003 study showed a benefit of K2 in slowing the growth of lung cancer and leukemia cells.
  • It is also shown to reduce the risk of and halt the growth of hepatocellular carcinoma, a dangerous type of liver cancer. (7)
  • It impairs the ability of cancer cells to stimulate tumor growth (8)
  • Stop the proliferation of cancer cells (9)

Life Extension Magazine reported that:

Lab studies demonstrate tremendous potential for vitamin K in many other cancer types as well. Vitamin K2 induces certain kinds of human leukemia cells to differentiate, or turn into normal white blood cells. In cells from certain brain tumors, in stomach cancer, and in colorectal cancer lines, vitamin K halts the reproductive cell cycle and induces apoptosis. Vitamin K also triggers a DNA-degrading protein that cancer cells normally suppress; thereby preventing tumor cells from repairing themselves effectively.

More research is definitely needed, but these initial studies show that Vitamin K may be an effective (and inexpensive) possibility for the future of cancer treatment.

6. For Brain Health

Some fascinating new research showed that the same process that makes Vitamin K helpful for preventing calcification of the arteries and muscle tissue might also make it beneficial for protecting the brain against Alzheimers and other diseases.

In short, the theory is that Vitamin K helps prevent excess calcium in the body (including the brain), and this excess disregulated calcium in the brain accounts for some of the damage from Alzheimers.

Another study looked at the dietary intake of Vitamin K in patients with early Alzheimers and found that those diagnosed with Alzheimers had considerably less Vitamin K than those in the control group. (10)

7. Longevity

We now know that Vitamin K affects 16 Gla-proteins in the body. This is one of the reasons that studies have consistently shown an inverse relationship between Vitamin K levels and mortality from all causes. (11) In other words, the better your Vitamin K levels, the less likely you are to die from all causes. (12)

In fact, the most recent study showed that those with the highest intake were 36% less likely to die from all causes than those with the lowest. (13, 14)

Of course, all of the above benefits show why it would logically have such an impact on mortality by reducing the risk of death from the main causes like atherosclerosis, osteoporosis, diabetes, and cancer, but it appears that there is a dose dependent correlation with Vitamin K intake:

Insufficient blood clotting was thought to be the main sign of vitamin K deficiency. However, scientists have since learned that you can have enough vitamin K to promote healthy blood clotting, yet still not have enough vitamin K for it to activate the Gla-proteins necessary to help prevent cardiovascular disease, osteoporosis, diabetes, and cancer, all conditions in which vitamin K-dependent proteins are known to be factors. Fortunately, studies show that vitamin K supplementation can significantly increase the amount of activated Gla-proteins in tissues—without over-activating the clotting proteins.(15)

8. Synthesis of Other Nutrients

I already mentioned how Vitamin K is needed for proper calcium synthesis (along with magnesium) but it is also needed in balance with Vitamin D3.

K2 and D3 work synergistically for many aspects of health. In fact, Calcium, Magnesium, K2 and D3 all work in balance. Taking too much D3 can cause a Magnesium deficiency without supplemental magnesium. Taking too much calcium can cause a magnesium deficiency or lead to over-calcification.

Vitamin D helps you absorb calcium, but K2 helps it actually end up in your bones and Magnesium helps make sure it gets there efficiently.

9. Skin Health & Anti-Aging

K2 is also promising for skin health and anti-aging. Just as it prevents the calcification of arteries, veins and soft tissue, it helps stop excess calcium in the elastin in the skin.

For this reason, K2 may help keep skin elastic and prevent wrinkles.(16)

2011 research showed that women with extensive wrinkles were also more likely to have low bones mass. Other research has shown that Japanese women were less likely to have wrinkles than other cultures, and noted the natto (fermented soy high in K2) in the diet of Japanese women.

How to Test for Vitamin K2 Deficiency?

You can measure serum K1 and K2, just like you can measure D3, but unfortunately, this is not extremely accurate, since K1 is held in the liver and has a short half life (about 4 hours). Essentially, a serum K test would only reveal Vitamin K levels from food intake in the last day or so.

There is a more advanced test, called the enzyme-linked immunosorbent assays (ELISA) that tests the presence of MGP. Initial reports on this test showed that almost 100% of people tested were deficient. The doctor who developed the test, Dr. Schurgers, suggests that almost everyone could benefit from increasing dietary and supplemental levels of K1 and K2.

How I Take Vitamin K2

Since there are no known side effects from K2 consumption, even at high levels, I take 180 mcg (two 90mcg capsules) per day on most days (consuming a small amount of Natto would also work). I also consume Fermented Cod Liver Oil Daily, which is a natural source of K2 (and other fat soluble vitamins), as well as Emu Oil (a natural source of K2). Raw butter from grass fed cows is also a good source of Vitamin K2 for those who tolerate dairy.

Some experts recommend as much as 500mcg per day, but I would only consume high levels like this under the guidance of a practitioner to make sure that cofactors (D3, calcium and magnesium) maintained proper levels as well.

For K1- I eat a lot of leafy greens and use nettle leaf (high in K1) in many of my homemade herbal teas.

Of course, since K2 is a fat soluble vitamin, it is important to check with a doctor before taking, especially at high doses of if pregnant or nursing. I also recommend this book for learning more about Vitamin K supplementation and safety.

Food Sources of Vitamin K

Food sources of Vitamin K2Food sources of K1:

  • Kale
  • Dried Basil
  • Spring Onions/Scallions
  • Broccoli
  • Brussels Sprouts
  • Asparagus
  • Cabbage
  • Cucumbers
  • Prunes
  • Most greens

Food sources of K2:

Bottom Line

I believe that Vitamin K2 is an unspoken and vitally important nutrient and that widespread deficiency could be related to the rapid rise in health problems we see in modern society.

Those who have any of the health problems associated with K2 deficiency (listed above) might consider doing their own research on K2 and talking to a qualified doctor of practitioner to see if it would be beneficial for their specific cases.

Have you ever used Vitamin K2? Did you notice any benefit? Share below!

Katie Wells Avatar

About Katie Wells

Katie Wells, CTNC, MCHC, Founder of Wellness Mama and Co-founder of Wellnesse, has a background in research, journalism, and nutrition. As a mom of six, she turned to research and took health into her own hands to find answers to her health problems. is the culmination of her thousands of hours of research and all posts are medically reviewed and verified by the Wellness Mama research team. Katie is also the author of the bestselling books The Wellness Mama Cookbook and The Wellness Mama 5-Step Lifestyle Detox.


82 responses to “Vitamin K2: 9 Uses and Benefits”

  1. Claire Avatar

    I recently discovered your blog and am really enjoying the wealth of information. I searched for varicose veins as that is one of my problems that I want to work on. I already eat healthier than I ever did growing up but would love to know more specifics for variscose veins. I’m in my 30s and despite perfecting my diet over the last few years I keep getting more veins. Spider veins are showing up more and more on my ankles and I have bigger veins behind my knees. It does worry me. A post on varicose veins would be so appreciated!

  2. Jake Toughill Avatar
    Jake Toughill

    It seems K2 is a fairly difficult nutrient to obtain. Looking at nutrient tables, there really isn’t any significant source of K2 except for Natto, but that’s a bit hard to find in America not to mention most people would find it unappetizing.

    I personally eat raw eggs, cheese, raw milk kefir, high vitamin butter oil, and a ton of pastured butter and I’m pretty sure I break the recommended intake by only a little bit.

    I’m guessing our ancestors obtained this from all the organ meats they ate. Possibly even bone marrow. Although there isn’t really any studies showing nutritional content of marrow.

    I can see how most people would be deficient in this.

  3. Catherine C Avatar
    Catherine C

    Could you address K3 just a little bit. When my son was born, I opted to not have him injected with vitamin K because of my research that it could be toxic for such little ones (at that time I wasn’t aware that there were several varieties and formats to getting Vitamin K into the body). What did you do for your children when they were born? Did you find a natural means for getting them vitamin K when they were born (either K1 or K2) or can mom’s levels of K during pregnancy help increase baby’s levels in early infancy (maybe through breastfeeding)? Thanks!

    1. Katie - Wellness Mama Avatar

      I didn’t give mine the K3 shots either for the same reason. I found that by consuming a lot of nettle and greens (k1) and taking k2 that my levels were high enough that I felt pretty safe for baby not needing the shot in a regular and gentle delivery. That said, I also did ora k2 drops that my midwife had. While there is widespread belief that baby can’t get k1/k2 through the placenta or through breastmilk, there is now a lot of speculation that this research was flawed because the women in the study didn’t have adequate levels themselves and were not able to pass on to baby. Definitely something you want to talk over with your doc or midwife, but that is what we did…

  4. Mary J Avatar
    Mary J

    Hi Katie, good to read about K2. I have been taking D3, and K2 but wondering what the ratio should be. I usually take about 60,000 D3 and 180mcg of K2. Does that sound enough K2? I have Hashimotos that the Dr has been giving me a mix of 65mg thyroid and dhea 15mg.
    dhea is in there because my cortisol is too low and apparently this has something to do with my Adrenals.
    Adrenal fatigue most likely.

  5. Darlene Avatar

    Been using vitamin K2, vitamin D3, strontium and boron for ages. I have fibrous dysplasia in my right femur (there is no bone marrow in the bone only fibrous tissue that continues to grow and causes the bone to expand, then it get extremely thin until it cracks or breaks) and it has helped greatly keeping the bone as strong as possible. The doctor was extremely surprised I was doing so well.

  6. Angie Avatar

    I’m surprised that parsley is not mentioned in this article. It has TWICE the vitamin K that kale has (and 4 times the folate), and is so easy to add to everything (and more pleasant, IMHO)!
    I keep a pair of 5-bladed scissors on my counter for that purpose. I also add it to smoothies and whole juice, and shred it along with carrots for salad.

  7. Marissa Avatar

    Hi Katie
    Love your articles! Would yogurt made from raw milk also be a good source of k2? Thanks!

  8. Bobbie Avatar

    Hi Katie,

    The K2 supplement you use has Soybean oil listed in other ingredients. Do you find this acceptable because it is Non-GMO?

  9. Courtney Avatar

    What is Natto? Is it a bean?

    Thanks as always for the wonderful information.

    1. Laura Avatar

      Fermented soy beans. It’s kinda gross but is awesome at killing yeast. I can take one tablespoon and the mild itching on my back goes away. Read about it. It’s amazing.

  10. melissa Avatar

    I want to hear that answer also. That is pretty much what we eat. We drink kombucha also and consume grass fed ghee. When I was taking vitamin D after 8 weeks I had the worse PMS ever. I think it may be the D (dr. Mercola says it is great though) not the K since we can’t overdose on K. I’ve also been reading the healthy home economist blog and eating all the raw smoothies may not be good for digestion also. Now I’m wondering if the green powders are good to add to my smoothies. I feel confused right now with all the info yet I do believe we are healthier on a We stone price type diet. What’s a girl to do? Lol

  11. Fay Avatar

    I am battling cancer for the 2nd time with alternative treatments and tried a really good supplement of K2. Even at the lowest dose of 1 pill per day, I still had incredible headaches and stomach upset. If anyone knows a way around this I would love to hear. My health had declined extremely with high weight loss, bone loss, leaky gut, etc. before they found the added problem that my breast cancer had returned. I am many foods intolerant and my cancer treatment protocols, along with type of cancer, mean no dairy, soy, and most dark (leafy green) vegetables. I am at a loss as to how consume K2 without more complications and symptoms but know I need it. Any input would be appreciated.

    1. Erik Avatar

      Seems like that leaves the highest sources of K2 as egg yolks and goose liver. You might also consider the synthetic form MK-4 supplements if the no soy or dairy issue is a problem for taking MK-7 supplements.

    2. Gillian Avatar

      Hello Fay, have you ever followed ‘My Dance with Cancer’ it is a personal story of someone who survived His fight with Cancer for many years (recently dying of heart relatated issues), it also has many links to other personal journeys following on from this. I hope I am not going off the K2 issue too much. It does seem like a valuable nutrient to be included to help with micro organisms from what I could follow in other studies and seemed to have helped with gut issues. This is purely my personal observation looking to prevent Cancer following family issues. So far, so good.

    3. Gillian Avatar

      Maybe you could ask your Doctor abour F M T. As you have such gut issues. It seems to be a successful new procedure. It’s something you could look into.

    4. Trena Avatar

      Sounds like you need to detox first and alkalize your body. Fastest way to do that is by drinking Ionized water. You can check it out at
      I had a large part of my tooth that was decayed. Noticed it from wearing invisiline. My dentist said I had to get it taken care of. I said let me try it naturally. He arrogantly said I couldn’t. Well, I started taking K2 with D3, calcium and magnesium, fermented cod liver oil with organic butter oil, grass fed beef bone broth, and I did oil pulling with unrefined coconut oil. My cavity is almost completely gone! I took pictures of it before too. I also stopped using toothpaste. I found out even if it has glycerin or glycerol in it it will coat your teeth and stop them from reminerizing..
      I will always take K2 from now on.

    5. Jennifer Avatar

      Wondering if you ever got any answers? My naturopath put me on D/K2 drops. I did the first ones yesterday and had the worse migraine and nausea! I thought it was a coincidence but was nervous to take more today. So I waited till later in the day. Again severe migraine.

      1. Tiffany Avatar

        Too much vitamin D will do that. Why not just get natto powder ( it’s a great food or smoothie mix in) and sit out in the sun while you have your morning tea, coffee or water for twenty minutes? Also eat a Brazil nut for selenium.

  12. Erik Avatar

    I’ve read that Gouda cheese is supposed to be a highest dairy source of K2, grass fed or not.

  13. Melissa Avatar


    Do you give this to your children? Or can the children recieve enough from ghee, milk, cod liver oil?

      1. Christina Avatar

        Katie, how early did you start giving K2 to your kids? I have a 3.5 year old and I would like to start giving her a low dose K2 supplement (45 mcg) but I am having a hard time finding recommendations on dosage and ages for children. I also am wondering if I should be giving her Vitamin D drops as well and how much. Our local doctors do not seem to be familiar with these types of supplements, so I am not sure where to look for advice.

        Also, I am a breastfeeding mama and am taking K2 and D as well, but am having a hard time finding out if there is a “safe” level for breastfeeding which I should not exceed. I still have tartar build-up on my teeth, so I believe that I should increase my dosage. If you have any thoughts or suggestions, that would be so helpful!

        1. Pam Avatar

          There’s a D3/K2 supplement made just for kids. Not sure if I’m allowed to mention brands on here.

  14. John Avatar

    When considering K2 – the form is important. Mk4 – is a synthetic K2 that the literature has shown you needs Mgs of while Mk7 – is a natural form that the literature shows only Mcg are needed (about 90 mcgs per day).

    1. Erik Avatar

      I believe the issue I read with synthetic MK-4 is that it doesn’t last more than a few hours after absorption so it needs to be taken more frequently.

      1. Bobby Avatar

        I believe the reason mk-4 doesn’t detect very long in the body is because your body loves it so much and puts it to use right away. I have not found the same to be true for mk-7. Mk-4 seems to be the superior choice- from my research and personal experience with both types in supplement form. The Japanese have some great studies that support my opinion that mk-4 is vastly superior to mk-7. The ideal dose seems to be 45mg/day of mk-4. Just thought I’d throw that out there for people to look into. Peace.

  15. Joli Tripp Avatar
    Joli Tripp

    I have been reading Dr. Mercola and Chris Kresser’s discussions of K2 but this was an easy to understand explanation. I will see my integrative medicine doc about K2, Calcium and magnesium.
    But what the heck is that a picture of? Yuk!

    1. Lauren Avatar

      Natto! It looks awful and I haven’t eaten it, but it is fermented soybeans, and they get real gooey and stretchy when they ferment. Supposed to be one of the only healthy ways to eat soy. I think an acquired taste as well! 🙂

  16. Roz K. Walker Avatar
    Roz K. Walker

    This is a very educational post. I didn’t know just how important vit K was for our bodies. I try to ensure I get enough K1, but will have to do something additional to ensure I get enough K2. Thanks for sharing this!

  17. Larena Gibbs Avatar
    Larena Gibbs

    I had been taking vitamin K2 and vitamin D3 together for a couple of months, however I noticed my thighs were painful. When I stopped the vitamins, I noticed the pain went away. I have been on magnesium citrate for years and I also take vitamin E sometimes. We eat grass-fed beef and drink raw milk, as well as eating a lot of leafy greens and some fermented foods (kimchi, kefir). Is it possible that the cramps and pain in my thighs were a sign of TOO much K2 or D3? The D3 was a high dose (10,000 IU) but I cannot remember the dosage of the K2.

    1. Erik Avatar

      Too much D3. There is no upper limit for K2 unless you have a medical condition needing blood thinners but the safe upper limit for D3 is 10000 IU outside medical dosages. That limit would include all supplements, food sources, and your own production of vitamin D.

  18. Dee Avatar

    Do you give this supplement to your kids? My daughter is on a regiment for the MTHFR gene mutation of vitamin d3, calcium & magnesium. I keep reading about the importance of vitamin k & know she needs it. My entire family is using supplements for this gene mutation but that’s a whole story in itself. I’ve asked her doctor if it would be wise to give her vitamin k & his response is that she gets it in her food. Only problem is this child would rather die than eat anything green….I mean anything! So while I might get some I feel she gets very little. Your article was very informative & helped shed more light on this topic. Any insight would be most appreciated.

    1. Katie - Wellness Mama Avatar

      It is one I always give to my kids, especially when supplementing with those three, mainly because it is really difficult to get enough K2 from food unless a person is consuming really large amounts of grass fed raw butter and organ meats.

      1. Lisa Avatar

        I am just starting to use Thorne research vitamin d and k2 drops (the one you recommended) but don’t know how much to give my kids. They are 5, 3, and 1. I couldn’t find anything on the Thorne website. Thanks.

  19. Kari C Avatar
    Kari C

    Thanks for this very informative post! I was just realizing that my vericose vein symptoms where related, at least in part, to vitamin K. Yesterday I ate a big spoonful of ghee and they quit hurting within half an hour. Thank you for the extra information!

  20. Jamie Avatar

    What are your thoughts on using K2/eating K foods with MTHFR? Could it pose a problem with clotting? I’ve never had any clots, but I’m homozygous for C677T, so I’m always cautious about K…

    1. Jamie Avatar

      I should add that I do consume leafy greens, raw dairy/butter, sauerkraut, use dried nettle in my pregnancy/nursing tea and when I have it on hand, use fermented cod liver as well.

      1. Stephanie Avatar

        Would you recommend mk7 from fermented soy if you have hypothyroidism? Thank you

    2. Katie - Wellness Mama Avatar

      I’ve never seen any evidence that it causes increased clotting (K1 does), but neither one has been shown to cause over-clotting. I’d definitely check with a doc though.

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